On Friday, former national security adviser Michael Flynn pleaded guilty to making false statements to the FBI. As part of his plea deal, he agreed to cooperate with an investigation into Russia's possible involvement in the presidential election.

In response, President Donald Trump told reporters he wasn't worried about what Flynn would tell investigators. He later tweeted that there was “nothing to hide” and he fired Flynn because he lied to Vice President Mike Pence and the FBI, not because he engaged in unlawful behavior.

During former FBI Director James Comey's prepared remarks for his Senate hearing in June, he said that Trump had a conversation with him after Trump fired Flynn.

Comey claimed Trump called Flynn a “good guy” who “has been through a lot” and asked that the then-FBI director let “Flynn go.”

“He repeated that Flynn hadn’t done anything wrong on his calls with the Russians, but had misled the vice president,” Comey said. “He then said, 'I hope you can see your way clear to letting this go, to letting Flynn go. He is a good guy. I hope you can let this go.'”

Critics said that if the president knew Flynn lied and asked Comey to not pursue an investigation, it could be an obstruction of justice. However, on Sunday, the president again denied he tried to convince Comey to turn a blind eye.